Dolan and Nadel are part of UC Irvine’s 90-plus study, one of the largest examinations of aging in the world.

Since 2003, the study has tracked the health of about 1,400 test subjects, each older than 90. The oldest living participant in the study is 106, but medical researchers have worked with one subject who lived to 108.

About 15 members of the study visited Crystal Cove State Park last weekend as part of the Crystal Cove Alliances’ Science and Nature at the Park program.

“The program works for us on a number of different levels,” said Harry Helling, Crystal Cove Alliance president. “It’s part of our efforts to bring scientific research into the park, and we’re also attracting nontraditional visitors to the park, who are seniors.”

Since 2003, the study has discovered links between exercise and longevity, as well as higher mortality rates among seniors who are underweight.

The study also has discovered that women are more likely than men to develop dementia.

People older than 90 are the fastest-growing segment of the population, and medical researchers are eager to learn more from aging Americans, said Dr. Claudia Kawas, who oversees the study at UC Irvine.

On Friday, medical researchers at Crystal Cove conducted tests on the seniors to measure their blood oxygen levels, as they did simple chair and walking exercises to raise their heart rates.

The data researchers collect from the tests will be used to study the connection between Alzheimer’s disease and blood oxygen levels.

“Why are we so phenomenal?” one study participant asked Kawas, as the group of nonagenarians gathered in one of the historic Crystal Cove cottages. Most of the participants in the study would have been in their teens when the cottage was built.

“Well, how many people do you know that live to be as old as you, but are still able to have such great conversations and know what’s going on?” Kawas said. “I’d have to say that’s pretty phenomenal.”